1. Field of the Invention
The present invention relates to a constant voltage power supply circuit for providing a stable voltage regardless of a load fluctuation, for example.
2. Description of the Related Art
Recently, there has been progressed a miniaturization and high-performance of a circuit such as mobile-type terminal device, and thus there has been required a miniaturization and high-performance on a power supply circuit there for.
Japanese Patent Publication (Kokai) 2000-284843 discloses a power supply circuit: a series regulator type power supply circuit for providing a stable voltage to electronic devices which are miniaturized in size and are operable at a low voltage, such as mobile-type terminal devices.
The series regulation power supply circuit disclosed in JP 2000-284843 has a stability in a low load condition, but deteriorates the PSRR (power supply rejection ratio) characteristics in a high frequency domain when the power supply voltage VDD is varied. Further, such the series regulator power supply circuit suffers from the disadvantages that the operation for providing a constant voltage can not followed at a high speed to the high speed load change.
Recent semiconductor devices for such as mobile-type terminal device are provided with a variety of circuits such as a communication circuit, illumination circuit, image processing circuit and data input/output circuit, and there has been strongly required a constant voltage power supply circuit enabling a provision of a stable voltage regardless of a fluctuation of loads such as those circuits.